A *subgroup* is some slice of a process array, formed by
restricting the process coordinates in one or more dimensions to
single values.

Suppose `i` is a location in a range distributed over a dimension
of group `p`. The expression

p / irepresents a smaller group--the slice of

Similarly, a *subrange* is a section of a range, parameterized by
a global index *triplet*. Logically, it represents a subset of the
locations of the original range.

The syntax for a subrange expression is

x [ 1 : 49 ]The symbol ``

Bryan Carpenter 2002-07-11